This project is designed to elucidate pathogenetic mechanisms in a rabbit model of chronic interstitial lung disease. Adjuvant requirements and cellular responses will be studied in a rabbit model of chronic alveolitis produced by chronic inhalation of an antigen and a soluble adjuvant (muramyl dipeptide). Unique handling by the lung of killed BCG organisms in saline is to be studied anatomically and immunologically, and compared to handling of particulate antigens not capable of producing interstitial pneumonitis. Immunogenetic and adjuvant requirements for etiologic agents in human interstitial pneumonitis may thereby be defined.